pushing people away

I promised myself I would stop pushing away people that love me or care for me, but I don't know how to stop. It's like breathing for me and comes naturally. I just wish I could stop. Within 1 yr i pushed away 2 guys that i liked because of my freaking high standards at the age of 16. I see my hot friends get into relationships so easily. As the ugly friend in all the groups i've been in i've always been the third wheel. Loving myself is so damn hard, people around me call me pretty or beautiful but i never felt that way about myself. I pushed away my guy best friend and we haven't talked in 3 months and his birthday is next month. I don't know if it would be weird if i said happy birthday. I think about him every day about where he is or how he is doing. I have Panick attacks every night since then it feels like the night terrors will never end. what am i doing so wrong that i've been kicked out of a group chat because i wasn't good enough? I value other people's lives but my own, I just don't care but it doesn't mean that i want to be alone.